Texas Parks & Wildlife Magazine   


July 2009 cover image Hamilton Pool

Flora Fact: Blue-Green Mystery

Sometimes found in Texas lakes, cyanobacteria may be the cause of several diseases, but new research could lead to a cure.

By Wendee Holtcamp

It may be one of science’s most impressive pieces of detective work. Biologists at the Institute for Ethnomedicine, led by Director Paul Alan Cox, believe they’ve found the culprit for ALS (Lou Gehrig’s disease) and other “tangle diseases” including Alzheimer’s, Parkinson’s disease and supranuclear palsy. The tiny neurotoxic molecule BMAA (β-N-methylamino-L-alanine) is produced by blue-green algae (also called cyanobacteria) found worldwide. The good news? The discovery could lead to a cure. The bad news? BMAA in drinking water could be a health risk even at low levels, but no one’s testing for it in water supplies yet.

“If you came to our lab right now, you would see a group of highly focused — even tense — scientists pushing as hard as we can for what we hope will open a new door towards novel approaches to [disease] therapy,” says Cox.

Along with famed neurologist/author Oliver Sacks and other colleagues, Cox theorized that BMAA gets consumed through drinking water or eating fish and becomes bound in brain protein, creating a neurotoxic reservoir. BMAA releases over time, causing neurodegenerative disease in genetically vulnerable individuals. Though not conclusively “proven,” data continue to accumulate, and Cox’s findings were recently verified by researchers at the University of Miami Brain Endowment Bank.

The story began in earnest in the 1950s when scientists descended on Guam to solve one of the world’s most alluring medical mysteries — why did the indigenous Chamorro people have 50 to 100 times the world’s average rates of ALS-like diseases? Scientists assumed they’d quickly find the cause, but decades of research led only to dashed hopes and controversy.

BMAA was first discovered in Guamanian cycad seeds, which the Chamorros pulverize into flour. Scientists then found BMAA concentrated in the brain tissue of disease victims, but were unsure how it might cause disease since it was consumed in low amounts.

And since BMAA was only known on Guam, how could it account for disease elsewhere? By the 1990s, Guam’s elevated ALS rates dropped, and most scientists studying the disease left. It seemed the puzzle would remain forever unsolved.

Then, in 2003, Cox linked many threads together in a daring twist on an old hypothesis. First he proposed that BMAA biomagnified through the food chain. Chamorros ate fruit-bats — skin, bones, brains and all. The bats ate cycad fruit, a tree whose roots contain cyanobacteria. The bats became endangered after guns became widespread, and Cox thinks their disappearance may explain the rapid decline in the disease’s prevalence. But the story soon got more exciting.

Cox knew that cycad roots harbor cyanobacteria, which seem to benefit the plants by fixing atmospheric nitrogen.

“Cox and I were driving in a car on Kauai after just leaving the lab,” his colleague Sandra Banack explains. “Then it hit us. It felt like our hearts stopped and time slowed down. Since cyanobacteria are free-living worldwide, this could be the link to sporadic ALS worldwide.”

They set out to test their hypothesis, but never imagined they’d not only find BMAA worldwide, but link it to other tangle diseases, as well.

It’s well known that cyanobacteria produce many toxins which cause fish kills, plus human and animal health impacts. TPWD even has a team dedicated to identifying and studying harmful algal blooms. Until now, scientists only knew of “acute effects” from cyanobacteria, in which toxins cause immediate problems. But this new research suggests chronic exposure to lower levels of BMAA can damage brain tissues, particularly in genetically vulnerable individuals.

“We realized that the BMAA molecule could be found at low levels in our water supplies,” says Banack. “We are developing commercial methods that can be easily used by municipalities, but they are not yet available.”

Some Texas municipal water supplies, such as Lake Houston, have had significant problems with cyanobacteria. The City of Houston has placed several Solarbee water circulators in the lake to help aerate the water. Lake Houston hasn’t seen large cyanobacteria blooms in the past two years, probably because heavy rainfall turns the lake into a flowing river.

Another promising development is legislation recently introduced to the Texas Senate (SB800) that would create a pilot program on the San Jacinto River to require sand mines to get permits and allow for regular monitoring. Sand mining violations on the river cause increased turbidity, which increases cyanobacteria outbreaks.

“You look at the west fork of the San Jacinto, there’s a big ol’ muddy plume coming into the reservoir. Waves of muddiness and turbidity extend down to mid-lake,” says TPWD’s Jeff Henson. “You see [blue-green algae] in turbid and stagnant waters.”

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